This work will be complementary to patch-clamp recordings of amino acid- activated single channel currents in outside-out patches excised from neurons in brain slices in comparison to amino acid-activated single channel currents in outside-out patches excised from cell in culture transiently transfected with specific subunits of excitatory amino acid receptors, thereby expressing only special recombinant receptor. I also propose to study long-term changes of excitatory synapses during normal and experimentally modified development in neurons of rat primary visual cortex. Finally, in light of experimental evidence for a role of neurotrophic factors underlying the plasticity of synaptic connections during development of the visual system, I will also study the effects of endogenously provided neurotrophins on AA-mediated synapses during normal development and during visual deprivation. Data obtained from these specific aims will permit the relative contributions of variations in the molecular forms of excitatory amino acid receptors to be distinguished as determinants of synaptic functions that underlie behavior and that are relevant in various CNS disorders.